I am also facing a similar question regarding to “one-to-many mapping”. I am working with information from EHR for a cohort of AIDS patients and I face situations like the one described in “data model conventions” (OMOP-CDM documentation):
ICD-9-CM code 070.43 ‘Hepatitis E with hepatic coma’ maps to the SNOMED concept for ‘Acute hepatitis E’ and a second SNOMED concept for ‘Hepatic coma’, in which case multiple CONDITION_OCCURRENCE records will be generated.
That is to say, it is necessary to enter two records in CONDITION_OCCURRENCE table: 197490 acute hepatitis E (SNOMED) and 377604 hepatic coma (SNOMED). Two records that represents a unique EHR source event!
I wonder: does this (decoupling) mechanism reflect the reality that the information in EHR conveys to us? Is it possible to apply any kind of additional mechanisms through which relink both facts (at least indirectly)?
Would it be possible (and recommended / necessary) to stablish a relationship through the FACT_RELATIONSHIP table, for instance, in this case, by using the relationships:
44818890 Finding associated with (SNOMED)
44818770 Has associated finding (SNOMED)
That is to say, a couple of records in FACT_RELATIONSHIP table:
Acute hepatitis E Finding associated with Hepatic coma
Hepatic coma Has associated finding Acute hepatitis E
I think in that way, CDM records may reflect much better the information contained in EHR.
Is this a correct approach? Is it a good practice?
Is there any other strategy to “relink” that kind of “decoupled” facts in CDM?
Many thanks in advance.